diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,11 @@
   - Indicate if changes are major, minor, or patch changes.
 ```
 
+## 0.4.0.1
+
+- [#11](https://github.com/haskell-github-trust/smtp-mail/pull/11) @spencerjanssen
+    - Support `crypton-connection-0.4.0`
+
 ## 0.4.0.0
 
 - [#5](https://github.com/haskell-github-trust/smtp-mail/pull/5) @spencerjanssen
diff --git a/Network/Mail/SMTP.hs b/Network/Mail/SMTP.hs
--- a/Network/Mail/SMTP.hs
+++ b/Network/Mail/SMTP.hs
@@ -77,6 +77,8 @@
 import qualified Data.Text.Lazy.Encoding as TL
 import Data.Text.Encoding
 
+import Data.Default.Class (def)
+
 data SMTPConnection = SMTPC !Conn.Connection ![ByteString]
 
 instance Eq SMTPConnection where
@@ -93,7 +95,7 @@
 connectSMTPSTARTTLS hostname = connectSMTPSTARTTLS' hostname 587
 
 defaultTlsSettings :: Conn.TLSSettings
-defaultTlsSettings =  Conn.TLSSettingsSimple False False False
+defaultTlsSettings =  def
 
 -- | Connect to an SMTP server with the specified host via SMTPS on port (465).
 -- According to RFC 8314 this should be preferred over STARTTLS if the server
diff --git a/smtp-mail.cabal b/smtp-mail.cabal
--- a/smtp-mail.cabal
+++ b/smtp-mail.cabal
@@ -1,5 +1,5 @@
 name:                smtp-mail
-version:             0.4.0.0
+version:             0.4.0.1
 synopsis:            Simple email sending via SMTP
 description:         This packages provides a simple interface for mail over SMTP. Please see the README for more information.
 homepage:            http://github.com/haskell-github-trust/smtp-mail
@@ -10,7 +10,7 @@
 -- copyright:
 category:            Network
 build-type:          Simple
-cabal-version:       >=1.10
+cabal-version:       2.0
 tested-with:         GHC ==9.6.4
 
 extra-source-files:
@@ -35,7 +35,8 @@
                , base16-bytestring
                , base64-bytestring
                , bytestring
-               , crypton-connection
+               , crypton-connection ^>= 0.3.1 || ^>= 0.4.0
+               , data-default-class ^>= 0.1.2.0
                , filepath
                , mime-mail
                , network